InterviewSolution
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InterviewSolution
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Consider the MB shown in the diagram, let the resistance X have temperature coefficient `alpha_(1)` and the resistance from the RB have the temperature coefficient `alpha_(2)`. Let the reading of the meter scale be 10 cm from the LHS. if the temperature of the two resistance increase by small temperature `DeltaT` then what is the shift in the position of the null point ? Neglect all the other changes in the bridge due to temperature rise.A. `9(alpha_(1)- alpha_(2))Delta T`B. `9(alpha_(1)+alpha_(2))Delta T`C. `1//9(alpha_(1) + alpha_(2))Delta T`D. `1//9(alpha_(1)-alpha_(2))Delta T` |
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Answer» Correct Answer - A `(X)/(10)=(90)/(90)rArr X=10Omega` `rArr (10(1+alpha_(1)DeltaT))/(10+Deltal)=(90(1+alpha_(2)DeltaT))/(90-Deltal)` `rArr(1+alpha_(1)DeltaT)(1+(Deltal)/(10))^(-1)=(1+alpha_(2)DeltaT)(1-(Deltal)/(90))` `rArr (1+alpha_(1)DeltaT)(1-(DeltaT)/(10))=(1+alpha_(2)DeltaT)(1+(Deltal)/(90))` `rArr1+alpha_(1)DeltaT-(Deltal)/(10)=1+alpha_(2)DeltaT+(Deltal)/(90)` `rArr(alpha_(1)-alpha_(2))DeltaT=(Deltal)/(9)rArrDeltal=9(alpha_(1)-alpha_(2))DeltaT` |
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